Jump to content

Sign in to follow this  
Chaos81

FMC Input

Recommended Posts

I was watching the ITVV 744 VA video last night and got to wondering how the WOB2F is inputed into the FMC.With the restrictions to be on the 301

Share this post


Link to post

In the FMC manual there is reference to the method of entry of a bearing/distance waypoint. Basically you can specify a waypoint that is 4DME London on the radial that intercepts the runway heading. The format is SOEMTHING LIKE LON269/04 (London VOR 269 radial 4Nm distance)Er, sorry if that doesn't make sense!The better way would be to download the sid/stars for EGLL from www.planepath.com or www.navdata.at, some clever spark will have already programmed this departure seeing as how it's one of the better known ones in the hobby!I think I might have to do VS19 this weekend actually, it's been a while. What with Ultimate Traffic installed now, I might even get a formation approach into KSFO.

Share this post


Link to post

>In the FMC manual there is reference to the method of entry>of a bearing/distance waypoint. Basically you can specify a>waypoint that is 4DME London on the radial that intercepts the>runway heading. The format is SOEMTHING LIKE LON269/04 (London>VOR 269 radial 4Nm distance)Thanks for the quick reply Mark.I realize you can put a bearing/distance waypoint in the FMC, but there is no bearing from LON. It's just a distance that is on the runway heading. My problem is, I don't understand where you are supposed to get the bearing from, as it is not on the chart.4DME from LON, you are supposed to be established on the 301

Share this post


Link to post

Sorry I wasn't 100% clear on the repsonse. What I mean is that if you wanted to program it yourself (and you probably wouldn't!) you'd have to work out where the 4miles DME london 'arc' bisected your runway heading after take off, whatever radial that intersection was on would then be the point on your flightpath at which you would intercept the 301 radial out of Burnham.Not sure if you've ever looked in a SID/STAR file but in there you'll see that it starts out by defining a number of custom waypoints specific to that airport's SID/STAR collection. One of the the many waypoints defined for EGLL in the procedures file will be that point 4 miles from the London beacon.

Share this post


Link to post

It looks like you are flying the WOBUN departure.This close, you would not be in LNAV. You would be hand flying or using runway heading on the MCP watching as a backup LON DME on your ND NAV 2. Your primary nav would show the bearing to the BUR ADF and when it hit 301 you would fly to BUR. You could use the LON DME to insure your distance limit as described in the text.The first waypoint on the LEGS page would be BUR and if you monitor your LEGS page it will read when the bearing hits 301 and MCP heading to it. You could do a direct to BUR at that point by the "double-bump" LLSK1 since BUR will be at the top of the stack and your path will be established at that point if you EXE it and engage LNAV although I would guess to would still be on MCP heading due to the quick progression.Notice that for 27L no LON DME is given at the turning point by a limit is described in the text.LON D4 is the max to get on the 301 radial for 27R and D3 is the max to turn onto the same radial for 27L. These are limits, not hard waypoints for the radial intersection.According to printed FMC docs that came with my CD package runways can be used as a nav fix so perhaps you can use a runway place/bearing intersect with the BUR 301 place bearing to create the turning point fix for guidance. I am not sure how to put a runway bearing into the scratchpad unless it is just RWY27R/BUR301 perhaps to define the intersect.I could use help on the last method for a runway :).

Share this post


Link to post

All it takes in the sid/star file to do it is this syntax:KEEP HDG UNTIL 4 FROM NAVAID LON (then whatever you do after LON etc)Someone link me to the chart and I'll post the code you'd need for the whole procedure. Anyway, pilots don't enter that sort of thing manually, it's already coded into the departure you select on the DEP/ARR page. (it's called a floating or psuedo waypoint)If you were flying it manually, you wouldn't make some custom fix at all - you'd just go to the FIX page, enter LON as the fix, and then /4 in one of the lines below to create a 4 DME circle around LON on the ND. Monitor this and the RMI as you depart and turn at the appropriate time. Pilots would probably set this up anyway even if they were letting LNAV fly it just for monitoring and situational awareness.

Share this post


Link to post

>These are limits, not hard waypoints for the radial intersection.You just summed up my issue in one sentence. I was thinking of those fixes as a hard waypoint, not as just a limit. DOH!>If you were flying it manually, you wouldn't make some custom fix at >all - you'd just go to the FIX page, enter LON as the fix, and then /4 >in one of the lines below to create a 4 DME circle around LON on the >ND. Monitor this and the RMI as you depart and turn at the appropriate >time.Thanks for the info Ryan, I didn't even think of doing it like that. This makes a whole lot more sense to me now. :)

Share this post


Link to post

unfortunately i think you need to register to get those charts, try VATSIMs resource section. The london 4DME etc is actually on the chart. They are little black lines over the departure route but this is actually built into your SID that you select from the DEP/ARR page. All you need to do is hard tune london and burnham into your NAV RAD page on the FMC. Flick your ADF1 indicator and VOR1 indicator on and you will see them show on the ND. On the dvd they are departing from runway 27R, and away from the London VOR, after take off they climb, at LON 4DME they make a right turn, if you are using the SID with LNAV then the autopilot will make that right turn at 4DME, you can check this out using your ND if you have london tuned in. The altitude constraints are programmed in also with the SID.

Share this post


Link to post

The DP I have actually for 27R shows the turn at LON 3 to be on the 301 radial by LON 4.Creating the 4 DME arc to give a visual range cue to show the turn completion limit for radial intersection is a great idea. Thanks also for the definition of a soft waypoint.As I recall I believe on the FMC fix or other page you can plot a radial, in this for BUR of the inverse of 301 (or is it not the inverse for an NDB), so on the ND that radial will be plotted as a backup guide to the RMI reading.One aside I'd like to mention is that I believe the reason soft waypoints are used in these situations is because of the minimum bank/roll limitations at initial climb IAS varying with the aircraft type and condition to avoid wing stalls, therefore stating that the turn radius (i.e. turn rate) might be different in each case. In the text DP section it is important to note if the limit is complete intersect or turn by DME NN or start turn by DME NN. These are not only for terrain avoidance but to maintain tight traffic patterns where airport seperation is poor in congested airport areas. I believe you have three majors plus London City tight in that area.

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  
×
×
  • Create New...